Hi Lisa
The liver produces bile all the time.
When you have finished digesting food the Sphincter of Oddi closes (Its a valve controlled by a muscle).
Bile backs up the common bile duct and starts filling up the gallbladder which is concentrating it fifteen fold.
At this time small debris may pass into the gallbladder but anything larger would impede to flow of bile and cause discomfort.
When the gallbladder is full, pressure builds, and bile is released from the Sphincter of Oddi. About 10%-25% of bile is leak out this way and recycled without contributing to food digestion.
Telman